Seal for electric apparatus.



F. G. KEYES.

SEAL FOR ELECTRIC APPARATUS.

APPLICATION FILED JULY], 1914.

Patented Dec. 24, 1918.

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FREDERICK G. REYES, OF EAST ORANGE, NEW JERSEY, ASSIGNGR T0 COQPERHEWITT ELECTRIC CQMPANY, OF HOBGKEN, NEW .1 ERSEY, A CURPORATXUN OF NEWJERSEY.

SEAL ELECTRIC APPARATUS.

aesaeie.

Specification of Letters Patent. Patented Death-24 191%.

Application filed. July 7, 1914. Serial No. 849,445.

To all whom it may concern:

Be it known that l, FREDERICK G. Ka ne,

a citizen of the United States, and resident of East Grange, county ofEssex, State of New Jersey, have invented certain new and usefulImprovements in Seals for Electric Apparatus, of which the following isa specification. 1

It has been proposed, notably by Charles A. Kraus in United StatesPatent No. 1,093,997, to construct a conducting seal for vacuumcontainers of a tube of conductive material sealed through the containerwall, the co-ellicient of thermal expansion of the tube being greaterthan that or the container p material.

It has also been proposed, for example by Byron E. Eldreol in UnitedStates Patent No. 1,083,070, to utilize for the conducting seal passingthrough the glass wall of a wire of high melting metallic material, saidwire being of a rate of expansion materially less than the wall andbeing held therein under compressive strain. in both the Kraus and theEldred patents the wall of the container is of vitreous material, suchas glass. I

The present invention has to do with the providing of a seal forcontainers of vitreous material, the material of the seal being in theform of a Composite tube whose coeflicient of thermal expansion lieswithin a region having aS its highest limit an expansion co-efiicientequal to that of glass or quartz, and an arrangement of the sealing andleading-in elements whereby the tendency of the current passing to heatthe sealing elements is avoided and greater current carrying capacity isobtained.

My invention is illustrated in the accompanying drawings in which Figure1 is a diagram showing the expansion curves of vitreous material such asmay form the substance of a vacuum container;

, Fig. 2 is a vertical section of a portion of said container having myimproved seal applied thereto and Fig. 3 is an enlarged transversesection thereof along the line 3,3 in Fig. 2.

in Fig. 1 the curve, 1, shows graphically the relation of the expansionof vitreous material, glass, for example, under the infiuence oftemperature. The vitreous material may be such as is shown at 2 in Figs.2' and 3 and within it may be arranged the it is well known, be soselected as to vary greatly its 'co-eflicient of expansion. From this itresults that the proportion may be' chosen which will cause its thermalexpansion to approximate that of the vitre us material. 2. When,therefore, the nic rel steel tube is closely surrounded by a tube ofplatinum, 6, as i's proposed herein, said latinum tube being securelywelded to the tube 5. the tubular structure as a whole will beapproximately the same in respect to expansion under heat as the glassor other vitreous material through which it is sealed. It may be lowerand still, owing to the elastic or yielding nature of the tubes 5' and6, they will adapt themselves to the external compression without injuryto the vitreous material.

The roundingoii of the seal at its outer end is accomplished by ametallic piece/7,

following the shape of a boss, 8, 'on the vitreous material 2, and alsoof the outer part of the tube 6, but separated from both, and a cap, 9,Welded to the end of the copper rod 3 and to the tubes 5 and 6. The diescribed conducting member is designed to be sealed into the glass, forexample, of a vacuum electric lamp.

The advantages arising fromthe use of my invention are based not merelyupon the materials chosen for the conducting memher, but also upon thefact that by the use of nickel steel in tubular form the said conductingmember is made elastic or yielding to a degree sufiicient for thepurposes of practical use. Moreover the beneficial eli'ect of thecoppercore in producing the contact with conducting material. inside thecontainer is heightened by the provision of a cooling space between itand the nickel steel tube within which it stands.

I have mentioned platinum as the material ot' the outer tube, but it isobvious that gold or any non-oxidizable metal of suiticiently highmelting point may be employed.

1 claim as-my invention:

1. The combination with a vacuum container ofnon-conductingma'terial,.of a com-Q.

steel inner tube and a platinum outer tube Welded thereto, thecoefficient of thermal ex pansion of the composite tube lying Within aregion Whose highest limit is equal tothe expansion coefficient of thecontainer material.

2. In a seal, a member of non-conducting material and a composite tubeof conductive material sealed through the non conducting member, thesaid composite tube comprising an inner tube of nickel steel and anouter tube of platinum, the coefiicient of thermal expansion of the tubelying Within a region whose highest limit is equal to, the expansioncoetlicient of the member through Which it is sealed.

3. The combination With a vacuum con- .t'ainer of vitreous material, ofa composite conducting tube consisting of a nickel steel inner tube anda platinum outer tube Welded thereto, the coellicient of thermalexpansion of the composite tube lying within a region Whose highestlimit is equal to the expansion coeliicient of the container material.

4. In a seal, a member of vitreous material and a composite tube ofconductive material sealed through the vitreous member, the saidcomposite tube comprising an inner tube of nickel steel and an outertube of platinum, the coeflicient of thermal. expansion of the tubelying Within a region Whose highest limit is equal to the expansioncoeflicient of the member through which it is sealed.

5. In a seal for vitreous material a conducting member comprising acentral copper rod, a tube of nickel steel surrounding the I same withan intervening space, an outer tube of platinum Welded to the aforesaidtube and a metallic cap uniting the said members by being sealedthereto.

6. The combination With a vacuum con tainer of non-conducting material,of a com- Lassen;

Within a region Whose highest limit is equal. to the expansioncoeilicient of the container material and a platinum outer tube Weldedthereto.

7. In a seal, a member of non-conducting material and a composite tubeof conductive material sealed through the non-conducting member, thesaid composite tube comprising a yielding inner tube having acoeflicient of thermal expansion lying Within a region whose highestlimit is equal to the expansion coeflicient of the member through Whichit is sealed and an outer tube of platinum.

8. The combination With a vacuum container of vitreous material, of acomposite conducting tube consisting of a'yielding inner tube of amaterial having a coefficient of thermal expansion lying Within a regionWhose highest limit is equal to the expansion coefficient of thecontainer material, and an outer platinum tube Welded thereto.

9. In a seal, a member of vitreous material and a composite tube ofconducting material sealed through the vitreous member, the saidcomposite tube comprising a yielding inner tube of a material having. acoeflicient of thermal expansion lying Within a. region whose highestlimit is equal to the expansion coeflicient of the member through whichit is sealed, and an outer tube of platinum.

Signed at New York, in the county of New York and State of N evv York,this 6th day of July, A. D. 1914.

FREDERICK G. KEYES. Witnesses:

* GEORGE H. STocKBRmen,

THOS. H. BROWN.

